1. Field of the Invention
This invention relates to the field of consumer devices, and in particular to techniques for preventing or discouraging the illicit duplication of copy protected material.
2. Description of Related Art
Techniques are continually being proposed and developed to prevent or discourage the illicit duplication of copy-protected material, such as commercial music recordings. These techniques generally attempt to limit the number of copies that can be made from a legitimate copy of the copy-protected material. At the same time, the purchaser of this legitimate copy expects to have unlimited rights for copying this material for his or her private purposes. For example, the typical purchaser has access to multiple means for playing and recording the material, and expects to be able to play the purchased material on each of these means, without constraints.
Increasingly common in the art is the use of flash memory cards to record content material for playback on small portable devices. These flash memory cards, or similar electronic memory devices, have an advantage over conventional recording media such as discs or tapes, in that they contain no moving parts and are thus more reliable and robust. Similarly, the playback devices for these memory cards need not contain movement mechanisms and are therefore also more reliable, robust, and, in general, less expensive than conventional players. The electronic memory devices and corresponding players are also generally much smaller than conventional discs or tapes and corresponding players, and generally consume less power, further increasing their suitability for use as portable playback systems.
The availability of small, inexpensive media for copying copy-protected material presents a number of potential problems as the rights of the provider of the copy-protected material are balanced with the rights of the purchaser of the copy-protected material. Because the medium is small, and intended for highly portable applications, the likelihood of the medium being lost, damaged, or misplaced is high. As such, the purchaser will expect to be able to reproduce the content material as often as required to replace the lost, damaged, or misplaced copies. Contrarily, because the media is inexpensive, the likelihood of an illicit mass reproduction of the content material is high, and the provider of the material will expect to be able to prevent such an illicit mass reproduction.
One method for limiting the ability to copy the content material is a xe2x80x9ccheck-out/check-inxe2x80x9d system. In this, as in other protection schemes presented herein, it is assumed that the copying and playback devices are xe2x80x9cconformingxe2x80x9d devices, in that they conform to the standards used to protect copy-protected material. When a copy of the material is made from a providing device to a portable medium, the conforming providing device prevents additional copies from being made until the portable medium containing the copy is returned to the providing device. This scheme has a number of drawbacks: if the portable copy is lost, damaged, or misplaced, it cannot be xe2x80x9creturnedxe2x80x9d to the providing device, and subsequent other copies cannot be made. Such a potential xe2x80x9cone time copyxe2x80x9d will not be acceptable to consumers at large. Conversely, multiple copies of the content material can be made directly from the portable copy, thereby obviating the protection benefits of this scheme. Similarly, although alternative schemes that allow for N simultaneous copies of the content material onto portable media may alleviate the consumer""s concern for copy-limitations, these schemes are equally susceptible to mass reproductions directly from the portable medium.
It is an object of this invention to provide a copy-protection method and system that balances the expected rights of the provider of copy-protected content material and the purchaser of this copy-protected content material. It is a further object of this invention to limit the loss of value incurred by a loss of the medium that contains copy-protected material. It is a further object of this invention to limit the economic feasibility of illicitly mass-producing copy-protected material.
These objects and others are achieved by associating a usage-limit with each copy of copy-protected material. A conforming playback device determines how much usage has been made of the copy, and only plays the copy-protected material if the usage is within the associated usage-limit of the copy. In a preferred embodiment of this invention, the providing source of the copy contains a total-usage-measure that is allocated among each of the provided copies of the copy-protected material, thereby allowing for more than one copy of the copy-protected material to be produced, or xe2x80x9cchecked-outxe2x80x9d from the providing source. When a copy of the copy-protected material is subsequently returned, or xe2x80x9cchecked-inxe2x80x9d to the providing source, the usage allocation associated with this copy is returned to the total-usage-value. In this manner, if a particular copy of the copy-protected material is lost, damaged, or misplaced, the loss of value to the purchaser is merely a reduction in the available total-usage. In a preferred embodiment, the parameters associated with the usage-limit are communicated via the copy of the material in a secure manner, so that an illicit provider cannot alter these parameters. Similarly, in a preferred embodiment, the parameters associated with the usage-limit are securely bound to the copy-protected material, so that an illicit provider cannot substitute illicit material for the copied material. Other security measures, such as an encryption of the copy-protected material, watermarking, ticketing, and the like, are also compatible with these aforementioned techniques, and are included in a preferred embodiment of this invention.